The present invention relates to a combustion control apparatus for an internal combustion engine having an exhaust gas purifier in an exhaust gas system of the engine, and specifically, relates to an apparatus for controlling combustion in engine cylinders based on a condition of the exhaust gas purifier.
Japanese Patent Application First Publication No. 2000-320386 shows a fuel injection control system for a diesel engine with a catalyst, in which a fuel quantity determined in accordance with a torque demand of the engine is split into a plurality of parts of fuel and the split parts of fuel are sprayed in a combustion chamber of the engine at predetermined intervals at fuel injection timing near compression top dead center in order to promote a rise in temperature of the catalyst.
In the fuel injection control system as described above, upon providing the second split fuel injection and the split fuel injection thereafter, the split fuel parts are sprayed into a flame in the combustion chamber which is produced by the first or previous split fuel injection. The split fuel parts sprayed upon and after the second split fuel injection cause mainly diffusive combustion. In the case of the mainly diffusive combustion, an air-fuel ratio locally becomes too low during decreasing the air-fuel ratio to lower than a stoichiometric air-fuel ratio, namely, varying the air-fuel ratio to a rich side. This causes a large amount of smoke to be generated.